The present invention relates to executing database queries in a hybrid Database Managements System (“DBMS”), and more particularly to consistent query execution in the DBMS.
A hybrid DBMS includes at least two database engines and at least two databases. Typically, at least a portion of the data of a first database is replicated to the second database, but where such data is organized and stored in a manner different than in the first database.
Typically, the two database engines and the way the data is stored and organized in the two databases are optimized for different types of queries. Usually, hybrid DBMSs categorize at least some of the incoming queries and execute each query on the engine that is predicted to be most suited for executing the query. A key challenge for such hybrid DBMSs is to ensure, with low computational overhead, data consistency and consistent computation of the same result irrespective of the engine used for performing the query.